Harris Platinum Z2 CD, Manual

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888-2406-002 1-3
WARNING: Disconnect primary power prior to servicing.
Introduction/Specifications
The Z-axis approach arranges the system RF components such as dividers,
combiners and amplifiers in three dimensions, to permit the most efficient possible
signal paths between them. The method allows the transmitter amplifying group to
be broken down economically into the smallest possible blocks for removal,
servicing and replacement. See Figure 4-1 (in Section IV) for overall block
diagram.
1.3.1 Harris DIGIT Digital FM Exciter
The Harris DIGIT FM exciter is supplied as standard equipment with all Platinum Z
transmitters. The DIGIT, with its digital input module, generates the complete
stereo FM waveform in the digital domain, using a digital signal processor (DSP) as
a stereo generator and composite limiter, and a 32-bit numerically controlled
oscillator (NCO) as a digital modulator. Digital techniques allow direct connection
of standard AES/EBU stereo audio data to the FM exciter to eliminate the distortion
and alignment problems of analog signal paths and analog FM exciters. DIGIT is
also available with an analog interface module for stations with analog program
paths, easily interchangeable with the digital module.
1.3.2 Harris SuperCiter Analog Exciter
The optional Harris SuperCiter is a 55 watt, high quality, analog exciter designed
for broadcasters needing state-of-the-art analog performance at a value price. The
SuperCiter combines time-proven PLL technology with modern RF amplifier
circuits to provide driving power of very high quality to any FM transmitter.
1.3.3 Redundant Exciters
Each transmitter includes one exciter in a basic version but allows space for a
second optional exciter with the needed exciter exchange autoswitching hardware
and control within the cabinet.
1.3.4 PA/IPA Modules
Each PA module contains a single RF PA on one side of the heatsink with the
opposite side empty. Each PA has two MOSFET devices mounted on a compact
heat spreading assembly, and is capable of providing up to 425 watts. The RF
modules plug directly into an isolated combiner without using channel sensitive RF
cables. PA modules are “hot-pluggable” and can be removed and inserted into an
operating transmitter without removing plugs and cables. Each PA module is
conservatively rated to produce over 375 watts of output power into a system
VSWR of 1.5:1 at up to 50
o
C ambient temperature at sea level.